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Full text of "Text Book Of Mechanical Engineering"

'V

i

774                               Appendix I.

~ 10° or - 30°, is exhausted to the storage chamber, from
•which, after doing duty, it is redrawn by the engine to supply
the compression cylinder. By this arrangement there is less
heat to abstract than if air at 60° were used, and an important
•economy results. The compression and expansion cylinders
must lie apart from the steam cylinder and from each other, and
all the pistons are connected to one crank shaft, which has,
-usually, a heavy fly wheel. -The parts required are therefore, in
-order :—Steam cylinder, compression cylinder with water jacket,
condenser, expansion cylinder (non-conducting), and storage
chamber (non-conducting).

At first sight it would appear that heat abstraction was
entirely due to the use of condenser and water jacket, but this
is only a part of the truth. Heat given during adiabatic com-
pression

x (diff of temp.)

diff. of temp.)
\n                           and,

'8

i * |                            Again,   condenser   and   jacket   remove   heat   at   constant

"                       pressure, and the amount

ffjf]                                                      = Kpx.(diff.-of temp.)

Also, heat removed during adiabatic expansion

= Kv x (dirl of temp.)

Assuming, as in the theoretical example, that rise of temp.
r f/                       during compression = fall of teijip. during expansion, the various

;4                       heats may be represented as follows .—

N = normal heat (atmospheric temperature)

1.  After compression, heat in gas

= N + Kv   (latter given by engine)

2.  After condensation, heat in gas

= N 4- KV — Kp (heat now in condenser = Kp)

3.   After expansion, heat in gas

_XT i tr       tr   _ IT

— JL^I T JVv ~" -P^p       JXV

«= N - Kp   (heat taken by engine = Kv)